Table 2.
Rate Ratios of Encephalopathy, Unspecified Dementia, and Combined Encephalopathy and Unspecified Dementia According to Cumulative Styrene Exposure Accrued During Different Exposure Time Periods Among 72,465 Workers of the Danish Reinforced Plastics Industry, 1977–2011
Encephalopathy | Unspecified Dementia | Combined Encephalopathy and Unspecified Dementia | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
Exposure Period and Cumulative Styrene Exposure | Person-Years | Cases | RR a | 95% CI | Cases | RR a | 95% CI | Cases | RR a | 95% CI |
<15 years prior, mg/m3-years | ||||||||||
0 | 635,123 | 93 | 1.00 | 466 | 1.00 | 559 | 1.00 | |||
<26 | 430,989 | 46 | 1.36 | 0.94, 1.98 | 56 | 0.89 | 0.66, 1.21 | 102 | 1.07 | 0.85, 1.34 |
≥26 | 430,482 | 89 | 1.67 | 1.17, 2.37 | 43 | 0.65 | 0.45, 0.94 | 132 | 1.09 | 0.86, 1.39 |
P for linear trend | <0.01 | 0.03 | 0.43 | |||||||
15–29 years prior, mg/m3-years | ||||||||||
0 | 872,793 | 117 | 1.00 | 273 | 1.00 | 390 | 1.00 | |||
<46 | 311,893 | 31 | 0.61 | 0.41, 0.93 | 125 | 1.01 | 0.81, 1.25 | 156 | 0.81 | 0.67, 0.98 |
≥46 | 311,908 | 80 | 1.42 | 1.04, 1.93 | 167 | 0.82 | 0.67, 1.01 | 247 | 0.87 | 0.73, 1.03 |
P for linear trend | 0.05 | 0.07 | 0.08 | |||||||
≥30 years prior, mg/m3-years | ||||||||||
0 | 1,305,496 | 201 | 1.00 | 296 | 1.00 | 497 | 1.00 | |||
<45 | 95,303 | 13 | 0.75 | 0.41, 1.37 | 106 | 1.08 | 0.85, 1.38 | 119 | 1.10 | 0.88, 1.38 |
≥45 | 95,795 | 14 | 0.80 | 0.45, 1.44 | 163 | 1.19 | 0.95, 1.48 | 177 | 1.21 | 0.98, 1.49 |
P for linear trend | 0.35 | 0.13 | 0.07 |
Abbreviations: CI, confidence interval; RR, rate ratio.
a Adjusted for age, calendar year, sex, level of education, hospitalizations related to chronic obstructive pulmonary disease, alcohol-related hospitalizations, and employment status.